West of the Luzon Strait is a hot spot where water and energy exchange are strongly influenced by the westward intrusion of Kuroshio flow.Shipboard observations carried out during spring 2010 quantify the upper ocean mixing in the region west of the Luzon Strait.The observations indicate strong turbulent mixing occurs in the upper 300 m near the Luzon Strait.Turbulent kinetic energy dissipation rates vary by four orders of magnitude, from the noise level to about O(10-6 W kg-1), and turbulent eddy diffusivity reaches O(10-2 m2 s1).This enhanced mixing is primarily associated with the shear unstable mechanism of the Kuroshio westward intrusion.It is revealed by in-situ observation that unstable current such as the Kuroshio west wing could induce strong mixing as large magnitude as that induced by internal tides and wind forcing.The dependency further shows the dissipation rates increase with increasing shear but decrease with increasing stratification in the observation region.